Which of the following describes a semifowler's position?

The semifowler's position is characterized by the patient being in a supine position with the head and upper body elevated at an angle of about 30 degrees. This position is commonly used in clinical settings for various reasons, including promoting comfort, easing respiratory function, and facilitating better digestion. It allows for a more relaxed posture while still providing support for the back and neck, making it beneficial for patients who may have difficulty breathing or who are recovering from surgery.

In contrast, lying flat on the back describes the supine position and does not involve any elevation of the head. Lying on the side with arms extended refers to the lateral position, which is appropriate for different clinical needs but does not match the semifowler's criteria. Finally, lying face down with the head turned describes the prone position, which serves specific medical purposes but is not related to the semifowler's position. Thus, the description of lying on the back with the head raised at an angle of 30 degrees is the accurate definition of semifowler's positioning.